1. Field of the Invention
The present invention relates to a recording head for emitting recording liquid from a discharge opening to generate flying droplets, thereby effecting recording, a substrate for said head, and a liquid emission recording apparatus equipped with said recording head.
2. Related Background Art
In the conventional liquid emission recording head, the common electrode of the wiring is constructed, for example, as disclosed in U.S. Pat. No. 4, 499,480. FIG. 1 is a schematic plan view of a substrate for the conventional liquid emission recording head, and FIG. 2 is a schematic cross sectional view along a line II--II' in FIG. 1, wherein shown is a substrate 11 for the liquid emission recording head. There are also shown a heat-generating resistor layer 3 composed of HfB.sub.2 and formed on a substrate 15; an aluminum wiring layer 4 for the common electrode; an aluminum layer 5 for the individual electrodes; an anti-oxidation protective layer 6 composed of SiO.sub.2 ; an anti-cavitation protective layer 7 composed of Ta; and an ink-resistant protective layer 8 composed of photosensitive polyimide. The heat-generating resistor layer 3, wiring layers 4, 5 and protective layers 6, 7, 8 constitute an electrothermal converting element for generating thermal energy to be utilized in the emission of liquid from the discharge opening.
After the principle portions of said substrate 11 for the liquid emission recording head are completed, a common electrode member 13 consisting of a copper-laminated glass-epoxy board is adhered to a broken-lined portion 12, and said common electrode member 13 and the common electrode wiring 4 are connected by wire bonding. This state is shown in FIG. 3 and FIG. 4 which a schematic cross-sectional view along a line IV--IV' in FIG. 3, in which same components as those shown in FIGS. 1 and 2 are represented by same numbers. In FIG. 4, there is shown a wire 14 connected by wire bonding.
However, such conventional structure, requiring the preparation of wiring member (common electrode 13 etc.) separate from the liquid emitting part and the subsequent connection of said wiring member for example wire bonding, is associated with the drawbacks of having a complex preparation procedure and the eventual disconnection of the wire bonding even after the completion of the procedure.
Particularly in the liquid emission recording head of the so-called full line type in which the discharge openings are provided corresponding to the full line width of the recording material, the number of wire bondings to corresponds to the number of said discharge openings. Consequently the process is very complex and requires high precision and secure operations, and the head is still associated with the drawbacks of increased possibility of wire disconnection because of the increased number of bonding wires and cumbersome preparation of the common electrode member corresponding to the width of said recording head.
U.S. Pat. No. 4,458,256 to Shirato, et al. relates to an ink jet recording apparatus including actuating portions and lead electrodes for conducting current. The lead electrodes are wired in such a manner that a conductive member is disposed on a surface which is at a side where the ink droplets are ejected. The conductive member is a part of the lead electrode, or one actuating portion is provided with a plurality of lead electrodes, and these electrodes are led, substantially in parallel, to terminals which are located at a side opposite to the ejection port with respect to the actuating portion, or one chamber is provided with a plurality of actuating portions which are separated from one another, and lead electrodes connected to the actuating portions are led, substantially in parallel, to terminals which are located at a side opposite to the ejection port with respect to the actuating portion, or the actuating portion is disposed on a conductive member intervened with an insulating layer and the conductive member is a part of the lead electrode. In one embodiment, the electrode lead and the terminal may be connected by means of a through hole.
Japanese Patent Publication No. 60-208,248 relates a heat generating resistance layer and a selection electrode which are laminated to the upper surface of a substrate. The heat generating resistance layer, a common electrode and a selection electrode are respectively patterned at desired positions in predetermined shape and size such that a heat generation part is arranged between a common electrode and the selection electrode. The common electrode is connected to the heat generating resistance layer at the terminal part thereof and this terminal part is integrated with a conductive support through the electrode in a through-hole while the selection electrode is arranged only to the upper surface of the substrate. Therefore, the common electrode and the selection electrodes are separately arranged to the front and back surfaces of the substrate through an insulating layer.